Ranma suddenly falls head over heels for Shampoo when she ties him to her with the magical Red Thread of Fate. Just a few more hours and the effect will be permanent, and Akane doesn't care one bit... does she?

Because of a gambling debt Ranma made ten years ago in a game of Old Maid, the gambling king occupies the Tendo dojo. But Ranma, who, like the gambling king, is a bad gambler himself, manages to win back the dojo through the same game by the act of cheating.